Biomedical subjects

L Mertens

Publications and source records attributed to L Mertens.

At least 19 recordsLinked to original sources

PubMed2006

Stenting of hypoplastic aortic segments with mild pressure gradients and arterial hypertension.

OBJECTIVE: To determine the safety, feasibility and effectiveness of stent expansion of hypoplastic aortic segments with pressure gradients in patients with arterial hypertension. DESIGN: Non-randomised prospective clinical trial. SETTING: Tertiary referral centre, congenital cardiac unit. PATIENT SELECTION: 20 consecutive patients (median age 14.5 years, range 11.6-38.8 years) with arterial hypertension and a hypoplastic segment of the aorta. Seventeen patients had successful previous arch interventions in a coarctation site. INTERVENTIONS: Stent deployment in hypoplastic arch segments. MAIN OUTCOME MEASURES: Gradient across the aortic arch; complications early and during follow up; residual hypertension. RESULTS: 23 stents were deployed: 13 in the cross and 10 in the isthmus. The mean gradient across the aortic arch decreased from 16 (SD 6) (median 17) to 3 (4) (median 1) mm Hg (p < 0.001). In a few patients a mild gradient persisted just distal to the left carotid artery due to residual orificial narrowing or acute angulation. No complications occurred during or after the procedure. During follow up of 2.2 years (range 0.2-4.8 years) arterial hypertension resolved in 10 patients and 10 required residual drug treatment with better control of blood pressures. CONCLUSIONS: Pressure loss due to residual hypoplastic aortic segments can be treated effectively and safely with stent expansion. Some patients remain mildly hypertensive and require additional drug treatment.

Adolescent↗

PubMed2003

Idebenone treatment in Friedreich's ataxia: neurological, cardiac, and biochemical monitoring.

The authors report 1-year prospective data on eight patients with Friedreich ataxia. Idebenone did not halt the progression of ataxia. At the end of therapy, cardiac ultrasound demonstrated significant reduction of cardiac hypertrophy in six of eight patients. Cardiac strain and strain rate imaging showed that the reduction of hypertrophy is preceded by an early and linear improvement in cardiac function. Idebenone reduced erythrocyte protoporphyrin IX levels in five of six patients with elevated baseline levels; however, changes did not consistently relate to cardiac improvement.

Adolescent↗

PubMed2003

Combined bronchoalveolar lavage and transbronchial lung biopsy: safety and yield in ventilated patients.

The aim of this study was to evaluate the safety and diagnostic yield of bedside bronchoalveolar lavage (BAL) combined with fibrescopic transbronchial lung biopsy (TBLB) in determining the aetiology of pulmonary infiltrates in mechanically ventilated patients. The records of 38 mechanically ventilated patients who underwent BAL/TBLB to investigate unexplained pulmonary infiltrates were retrospectively reviewed. Patients were divided into two groups: immunocompetent (group 1: n = 22; group 1a: n = 11, late acute respiratory distress syndrome (ARDS); group 1b: n = 11, no ARDS) and immunocompromised (group 2, n=16). The procedure allowed a diagnosis in 28 patients (74%), inducing therapeutic modification in 24 (63%) and confirmation of clinical diagnosis in four (11%). In groups 1a, 1b and 2, diagnosis was obtained in 11 out of 11 (fibroproliferation), seven out of 11 and 10 out of 16 patients, and therapy changed in 11 out of 11 (administration of steroids), six out of 11 and seven out of 16 patients, respectively. Pneumothorax occurred in nine patients (four of group 1a), bleeding in four (<35 mL), and transient hypotension in two. No fatalities were procedure-related. Combined bronchoalveolar lavage/transbronchial lung biopsy is of diagnostic and therapeutic value in mechanically ventilated patients with unexplained pulmonary infiltrates, excluding those with late acute respiratory distress syndrome. Although complications are to be expected, the benefits of the procedure appear to exceed the risks in patients in whom a histological diagnosis is deemed necessary.

Adult↗

PubMed2002

Severe IgE-mediated anaphylaxis following consumption of fried frog legs: definition of alpha-parvalbumin as the allergen in cause.

BACKGROUND: IgE-mediated allergic reactions to bullfrog and edible frog have been reported. The implicated allergens have not been defined so far. The frog material and the patient's serum from a case of severe food-induced anaphylaxis were used to define the implicated allergen at the protein and DNA level. METHODS: Immunoblotting techniques and N-terminal protein microsequencing were used to define the allergen recognized by the patient's serum. Back translation from the identified protein sequence was used to design degenerated primers to amplify the allergen's cDNA by polymerase chain reaction (PCR). We defined the nucleotide sequence of the allergen from the frog of Indonesian origin that was consumed by the patient, and the homologous cDNA from Rana esculenta. RESULTS: Protein microsequencing revealed that the implicated frog allergen belonged to the parvalbumin family. cDNAs coding for alpha- and beta-parvalbumin of R. esculenta and Rana species were cloned. Recombinant proteins were expressed in Escherichia coli. The patient's serum IgE antibodies recognized parvalbumin prepared from frog muscle and recombinant alpha-parvalbumin from R. species but not from R. esculenta. Recombinant beta-parvalbumin was not recognized by the IgE antibodies. CONCLUSION: This work defines at the protein and DNA levels alpha-parvalbumin as the allergen implicated in a case of IgE-mediated anaphylaxis to frog muscle. It also shows that a protein belonging to the parvalbumin family is implicated in type I allergies outside the fish species.

Allergens↗

PubMed2001

Quantitation of localized abnormal deformation in asymmetric nonobstructive hypertrophic cardiomyopathy: a velocity, strain rate, and strain Doppler myocardial imaging study.

We report a case of a 10-year-old child with nonobstructive hypertrophic cardiomyopathy in whom two-dimensional echocardiography showed asymmetric septal hypertrophy with a localized thickening in the mid-septal segment. Systolic regional longitudinal motion and deformation indices were quantified by the new ultrasound-based parameters velocity, strain rate, and strain. Regional longitudinal myocardial function indices were normal for the basal and apical septal segments. The deformation parameters strain rate and strain (not the regional velocity profile) were abnormal only in the hypertrophied mid-septal segment with myofibril disarray. The concepts and advantages and clinical implications behind this quantitative approach to localizing and quantifying areas of abnormal deformation related to such myocardial disarray in localized hypertrophy are discussed.

Biomechanical Phenomena↗

PubMed2001

Recurrent involvement of chromosomal region 6q21 in heterotaxy.

We present a patient with heterotaxy and a de novo, apparently balanced reciprocal translocation with breakpoints at 6q21 and 20p13. Another patient with heterotaxy was previously reported with a de novo balanced translocation involving chromosome band 6q21. The breakpoints in both patients on 6q21 were found to be located in the same chromosomal region spanning maximally 2 Mb. We speculate that the two breakpoints lead to the disruption of the function of a single gene, either directly or through long distance effects. Alternatively, the present observation suggests additional heterogeneity in heterotaxy in humans.

Abnormalities, Multiple↗

PubMed2001

Long-term assessment and serial evaluation of cardiorespiratory exercise performance and cardiac function in patients with atrial switch operation for complete transposition.

BACKGROUND: At present, a considerable number of patients survive who underwent an atrial switch operation for correction of complete transposition. Our study aimed to assess their long-term exercise performance and the serial evolution of cardiac function. METHODS: We studied 22 patients 5 to 17 years after an atrial switch operation, and followed them serially for 3.5 +/- 2 years after the first evaluation. Cardiorespiratory exercise function was assessed by analysis of gas exhange and by determination of the ventilatory anaerobic threshold. Echocardiography was performed on all evaluations. RESULTS: All patients were in Class I of the classification of the New York Heart Association at all assessments. Ventilatory anaerobic threshold, however, was significantly lower than normal. It averaged 77.9% +/- 13.7 of the normal mean value at the initial evaluation, and remained stable when re-evaluated later (76.2 +/- 13.7%). At the initial study, the increase in oxygen uptake during graded exercise was below the 95% confidence limit in 6 of the patients, and was below this level in 10 patients at re-assessment. The subnormal values for oxygen uptake during submaximal exercise were associated with moderate to severe haemodynamic dysfunction. At echocardiography, 15 of 17 patients studied twice had mild to moderate right ventricular dilation and tricuspidregurgiation, which remained virtually the same at reasssesment. A stable sinus rhythm was initially present in 17 patients, and persisted in 15 patients during follow-up. CONCLUSION: At medium term follow-up, cardiorespiratory exercise performance remains stable in patients after atrial switch repair. Serial exercise testing appears useful, because in individual patients in the present study, a decreasing exercise tolerance correlated with development of haemodynamic sequels.

Adolescent↗

PubMed2001

Left ventricular function before and after repair of an anomalous left coronary artery arising from the pulmonary trunk.

We report an infant with an abnormal left coronary artery arising from the pulmonary trunk in whom, subsequent to surgical repair, sequential improvements in regional left and right systolic and diastolic myocardial function were quantified by the new ultrasound-based method of regional strain and strain rate imaging. The regional radial and longitudinal myocardial function of the left ventricle was homogeneously reduced prior to repair, while the time course of their recovery differed subsequent to repair. We discuss the concepts and advantages behind this quantitative approach to monitoring regional myocardial function in children.

Aortic Valve↗

PubMed2001

Use of a cutting balloon catheter to dilate resistant stenoses in major aortic-to-pulmonary collateral arteries.

We report the successful use of a cutting-balloon catheter in dilating stenoses in major systemic-to-pulmonary collateral arteries which had been resistant to high pressure balloons. After dilation using the cutting balloon, we implanted stents to produce a marked improvement in both pulmonary blood flow and arterial saturation. The technique provides useful palliation for patients having such stenotic collateral arteries.

Angioplasty, Balloon↗

PubMed2001

Cardiorespiratory exercise function after the arterial switch operation for transposition of the great arteries.

AIMS: This study compares the functional outcome and cardiorespiratory response to exercise, in patients who have undergone arterial switch for transposition of the great arteries, with normal controls and patients who have undergone atrial switch operation. METHODS AND RESULTS: Fifteen patients who had undergone arterial switch (mean age 8.5+/-2.9 years) were compared to 32 patients who had undergone atrial switch (9.2+/-1.8 years) and 27 normal controls (8.5+/-2.1 years). Exercise testing was performed on a treadmill and gas exchange measured breath-by-breath. Aerobic capacity, assessed by determination of the ventilatory anaerobic threshold, averaged 91+/-7.8% of normal (95% confidence limits: 92-108%) for arterial switch and 75.1+/-13.1% for atrial switch (P<0.001 patients vs normals). Aerobic exercise function was evaluated by calculation of the slope of oxygen uptake vs exercise intensity. The mean value for this slope was 2.0+/-0.25 for arterial switch, 2.5+/-0.46 for normals and 1.7+/-0.80 for atrial switch (P<0.05; patients vs normals). Efficiency of the pulmonary gas exchange was assessed by calculation of the slope of ventilation vs carbon dioxide output during exercise. This averaged 38.7+/-14.7 for arterial switch, 48.1+/-14.1 for atrial switch and 30.3+/-7.6 for normals (P<0.001; patients vs normals). CONCLUSION: Cardiorespiratory exercise function is at, or slightly below, the lower limit of normal in patients with arterial switch, while the lowest values were observed for those who had undergone atrial switch.

Child↗

PubMed2001

Severe tricuspid regurgitation 14 years after diagnosis of "transient neonatal tricuspid regurgitation".

A 14 year old girl presented with severe tricuspid regurgitation after she was diagnosed with "transient tricuspid regurgitation of the newborn". In the neonatal period she had presented with severe tricuspid regurgitation without an obvious underlying anatomical cause. This spontaneously regressed during the first months of life. She was dismissed from follow up at the age of 5 years after complete normalisation of the clinical and echocardiographic examination. The subsequent evolution and management of the patient, as well as the possible pathogenesis responsible for the unusual clinical course, is discussed. This case stresses the importance of long term follow up of patients with transient tricuspid regurgitation.

Female↗

PubMed2000

Oxygen uptake versus exercise intensity: a new concept in assessing cardiovascular exercise function in patients with congenital heart disease.

OBJECTIVE: To assess the relation between exercise intensity and oxygen uptake during graded exercise in paediatric patients who underwent surgical repair of congenital heart disease, and to compare it with conventional measures of aerobic exercise function. DESIGN: Cross sectional study. Exercise testing was performed on a treadmill and gas exchange was measured on a breath by breath basis. PATIENTS: 29 patients who underwent an atrial switch operation for transposition of the great arteries (TGA) (mean (SD) age at testing 10.3 (2.5) years) and 30 patients who underwent total repair of tetralogy of Fallot (TF) (age 12.1 (3.3) years) performed graded exercise testing. Exercise responses were compared with data obtained in 24 normal controls (age 11.4 (2.6) years). RESULTS: The slope of oxygen uptake versus exercise intensity averaged 1.50 (0. 64) ml O(2)/min(2)/kg in the patients with TGA and 1.68 (0.75) ml O(2)/min(2)/kg after TF repair, both lower (p < 0.005) than in normal controls (2.42 (0.68) ml O(2)/min(2)/kg). The lower slope of oxygen uptake was correlated with a subnormal value for ventilatory anaerobic threshold, which averaged 78.0 (13.3)% of normal in TGA and 85.1 (10.6)% in TF. This was associated with a steeper slope (p = 0.001) of carbon dioxide output versus oxygen uptake above the ventilatory anaerobic threshold in TGA (1.26 (0.20)) and TF (1.20 (0. 18)) compared with the normal controls (1.05 (0.13)), and also a steeper slope of ventilation versus carbon dioxide in TGA (47.0 (15. 4)) and TF (41.5 (13.7)) than in the controls (30.3 (8.5)). CONCLUSIONS: Calculation of the steepness of the slope of oxygen uptake versus exercise intensity is a valid measurement of oxygen flow to the exercising tissues, which may be limited in congenital heart disease.

Adolescent↗

PubMed1998

Protein-losing enteropathy after the Fontan operation: an international multicenter study. PLE study group.

OBJECTIVE: This multicenter study retrospectively analyzes the data on 114 patients with protein-losing enteropathy after Fontan-type surgery. Special attention was given to the different treatment strategies used and their effect on outcome. METHODS AND RESULTS: In 35 participating centers 3029 Fontan operations were performed. The incidence of protein-losing enteropathy in the survivors was 3.7%. The median age at Fontan-type surgery was 8.2 years (range: 0.6 to 32.9 years). Median age at diagnosis of protein-losing enteropathy was 11.7 years with a median time interval between surgery and diagnosis of 2.7 years (range: 0.1 to 16.4 years). Most patients had edema (79%) and effusions (75%). Hemodynamic data revealed a mean right atrial pressure of 17 +/- SD 5.3 mm Hg with a cardiac index of 2.4 +/- 0.8 L/min/m2. Medical treatment only (n = 52) resulted in a complete resolution of symptoms in 25%, no improvement in 29%, and death in 46%. Surgical treatment (n = 52) was associated with relief of protein-losing enteropathy in 19%, no improvement in 19%, and death in 62%. In 13 patients 16 percutaneous interventions were performed. This resulted in symptomatic improvement after 12 interventions and no improvement after 4 interventions. CONCLUSIONS: We conclude that the current treatment of protein-losing enteropathy after Fontan operation is associated with a very high mortality and morbidity rate. Preventive strategies and new therapeutic approaches are necessary.

Adolescent↗

PubMed1998

Ventilatory inefficiency for carbon dioxide during exercise in patients with pulmonary hypertension.

The purpose of this study was to analyse the ventilatory efficiency for carbon dioxide (CO2) in the assessment of exercise tolerance in patients with pulmonary hypertension. Two groups of patients were studied. One group consisted of 37 patients with normal pulmonary artery pressure who underwent surgical closure of a left-to-right shunt. Another group was composed of 10 patients with pulmonary hypertension. Both patient groups were compared with the mean value of an age-matched pool of normal control subjects. Aerobic exercise performance was assessed by determination of the ventilatory threshold. The ventilatory efficiency for CO2 was assessed by calculating the slope of ventilation over carbon dioxide below the ventilatory threshold. The slope of ventilation vs. carbon dioxide output in patients with pulmonary hypertension (48 +/- 12) was steeper than the slope (31.3 +/- 7.0) in patients with normal pulmonary artery pressure (P < 0.05). Significant correlations (P < 0.05) were found between the pulmonary artery pressure and the slope of pulmonary ventilation over carbon dioxide (r = 0.92) and also with the physiological dead space-tidal volume ratio at maximal exercise (r = 0.55). This was associated with a severe reduction in exercise performance in patients with pulmonary hypertension, whereas in patients with normal pulmonary artery pressure it was only slightly below the lower limit of normal. These results demonstrate that patients with pulmonary hypertension have an inefficient ventilatory response to metabolically produced CO2 during exercise, which severely limits exercise tolerance.

Adolescent↗

PubMed1998

Percutaneous treatment of stenosed major aortopulmonary collaterals with balloon dilatation and stenting: what can be achieved?

BACKGROUND: The natural history of major aortopulmonary collateral arteries (MAPCAs) in patients with pulmonary atresia and ventricular septal defect (PA-VSD) is frequently complicated by progressive stenosis, leading to pulmonary hypoperfusion and debilitating hypoxaemia. OBJECTIVE: To evaluate balloon dilatation and stenting for relief of stenoses and improvement of pulmonary flow in patients with PA-VSD. DESIGN: Retrospective analysis of all patients where dilatation of MAPCA stenoses was attempted. PATIENTS: Twelve patients with stenotic MAPCAs. INTERVENTIONS: Dilatation was attempted in 25 stenoses. Vessels were stented if elastic recoil was noticed (n = 3), in the presence of long segment stenosis (n = 4) or marked tortuosity (n = 1). MAIN OUTCOME MEASURES: Diameter of stenoses before and after dilatation as well as arterial oxygen saturation data. Patients proceeding to surgical therapy. RESULTS: Two stenosed MAPCAs could not be crossed by a catheter. Four lesions were non-dilatable despite the use of high inflation pressures (18 atm). Six stenoses could be completely dilatated using angioplasty only; in five, only partial dilatation was obtained; eight stenoses needed stenting. In the group with partial expansion the mean (SD) diameter increased from 1.7 (0.8) to 3.5 (1.7) mm (p < 0.05); where full dilatation was achieved it increased from 2.1 (0.8) to 4.8 (1.9) mm (p < 0.05); and in the stented group in increased from 2.3 (0.9) to 5.0 (2.5) mm (p < 0.01). Percutaneous arterial oxygen saturation increased from 75(8%) to 82(8)% (p < 0.001). No complications were experienced during the procedures. Repeat dilatation was attempted in six stenoses, but only two procedures were successful. There were two episodes of vasospasm and in one an aneurysm had developed after redilatation. Two patients proceeded to outflow plasty and two subsequently had a unifocalisation procedure. CONCLUSIONS: Pulmonary blood flow can be improved using balloon angioplasty or stents in patients with stenotic MAPCA; however, 17% of the lesions were not dilatable. Procedures are generally safe, but carry a small risk of vasospasm, dissection, occlusion or aneurysm formation.

Adolescent↗

PubMed1998

Self expandable stents for relief of venous baffle obstruction after the Mustard operation.

OBJECTIVE: Obstruction of the venous pathways after Mustard repair for transposition of the great arteries is associated with an increased risk of arrhythmia and sudden death. The purpose of this study was to assess the effectiveness of the largest (tracheal 22 x 40 mm) Wallstents in treating baffle obstructions. DESIGN: Retrospective analysis of patients with stented venous pathways. SUBJECTS: Eleven patients with baffle obstruction after Mustard repair for transposition of the great arteries. INTERVENTIONS: Stenoses were dilated with an 18 or 20 mm balloon. However, recoil was noticed in 11 patients: immediately (n = 7) or on repeat angiography (n = 4). Eighteen stents were implanted (mean (SD)) 18 (3.3) years postoperatively. After dilatation a tracheal Wallstent (11.5 F) was deployed. MAIN OUTCOME MEASURES: Relief of obstruction, haemodynamic improvement. RESULTS: In the inferior vena cava, 10 stents were deployed in seven baffle obstructions with an increase in diameter from 9.8 (2.4) mm to 16.5 (1.4) mm (p < 0.01) and a mean (SD) pressure gradient decrease from 5.1 (3.6) mm Hg to 1.4 (2.0) mm Hg; in the superior vena cava, eight stents were implanted increasing the diameter from 9.1 (3.7) mm to 15.6 (3.8) mm (p < 0.001) with a decrease in mean pressure gradient from 5.1 (2.7) mm Hg to 1.9 (1.5) mm Hg. No complications were experienced during implantation. No anticoagulation was prescribed. During follow up (1.7 (0.6) years; range, 0.9-2.6) no problems were noted; five patients were re-catheterised without change in measurements. There was no evidence of peal formation in any of the stents. CONCLUSION: It is concluded that Wallstents are safe, easy to use, and effective in relieving baffle obstruction. Anticoagulation does not seem necessary.

Adolescent↗

PubMed1997

Sequence elements surrounding the acceptor site suppress alternative splicing of the sarco/endoplasmic reticulum Ca2+-ATPase 2 gene transcript.

Expression of the muscle-specific 2a isoform of the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA2) requires activation of an inefficient optional splice process at the 3' end of the primary gene transcript. The sequence elements required for this regulated splice event were studied by modifying a minigene containing the 3' end of the SERCA2 gene. An important requirement appears to be a strong muscle-specific acceptor site, as replacing it by a weak one prevented the induction of muscle-type splicing during myogenic differentiation. The induction of muscle-type splicing did not depend on positive cis-active sequences in the muscle-specific exon. On the other hand, replacement of a broad region around the acceptor site dramatically deregulated the expression pattern, as this modification strongly induced muscle-type splicing in undifferentiated muscle cells and in fibroblasts. This cis-active region is also involved in the suppression of the neuronal type of splicing. Furthermore selective replacement of the acceptor site as well as deletions or replacements in the muscle-specific exon induced muscle-type splicing to various extents in undifferentiated myogenic cells. Therefore sequence elements in the distal part of the optional intron and in the muscle-specific exon contribute to the suppression of muscle-specific SERCA2 splicing.

Alternative Splicing↗

PubMed1997

Assessment of cardiorespiratory exercise function in obese children and adolescents by body mass-independent parameters.

The parameters used to assess aerobic exercise function by gas exchange are usually adjusted for body mass and are expressed as millilitres per minute per kilogram. In the case of obese children this could lead to overcorrection with an underestimation of their exercise capacity. The purpose of the present study was to assess cardiorespiratory exercise function in obese subjects using body mass-independent parameters. As both carbon dioxide output (VCO2) and oxygen uptake (VO2) are usually corrected for body mass, the slope of VCO2 versus VO2 can be considered to be independent of body mass. This slope was calculated below the ventilatory threshold (S1) and above the ventilatory threshold (S3). Exercise tests were performed on a treadmill and respiratory gas exchange was measured breath-by-breath. A group of 29 obese children [mean age 11 (SD 2.5) years] were compared to 16 normal controls of the same age range [mean age 10.8 (SD 2.2); P > 0.05]. The patients were overweight by 36 (SD 17.9)% and had a body mass index of 25.0 (SD 3.8). The results showed that S3 in the obese subjects was significantly steeper compared to the normal controls [1.30 (SD 0.20) vs 1.10 (SD 0.20); P < 0.05]. The steepest values for S3 were found in the subjects with the highest degree of obesity. This method has some limitations, since in a large proportion of the patients (48%) no ventilatory threshold could be detected, which is prerequisite for calculation of these slopes. The latter was already suppressed at the onset of exercise in 21% of the sample or could not be detected because of breathing irregularity in 27%. It is suggested from this study that cardiorespiratory exercise function in obese children is reduced, especially when assessed by parameters of aerobic exercise which cancel the confounding effect of body mass.

Adolescent↗